-Both do the job of fuelling and ignition fine
-Megasquirt can do COP/wastedspark more easily
-Megasquirt also has autotune
-Megasquirt has full support for a wideband, this is a BIG minus for Cossie
-It is easier to hook up things like rad fans, water injection, etc. to the Megasquirt.
-Cossie is fully sequential as standard, MS (MS2 only) only with upgraded firmware.
-Cossie is ok if you tune it once, then just drive for years.
-MS works right away with either the RST distributor or the cvh-efi flywheel triggering, Cossie always needs its own dual-trigger scheme. Doing this DIY can be unreliable.
-MS is so easy when you want to change a setting, like the temperature where fans kick in, literally a one minute job.
-MS has the ability for anyone to record datalogs and there are software to analyze them later.
-MS is only an option for people who are able to search for and follow instructions and don't expect a plug and play install.
-After the MS is installed and set-up, it's at least just as reliable to drive and forget.
-If killed, the MS can be easily repaired by anyone for a fiver. As all the repair instructions, schematic drawings and test sequencies are available.


Happy choosing.